diff --git a/mercurial/ui.py b/mercurial/ui.py
--- a/mercurial/ui.py
+++ b/mercurial/ui.py
@@ -792,6 +792,8 @@
                 itemdefault = item.default()
             else:
                 itemdefault = item.default
+            if isinstance(itemdefault, list):
+                itemdefault = ' '.join(itemdefault)
         return itemdefault
 
     def hasconfig(self, section, name, untrusted=False):